The present invention relates to the purification of drinking water, and more particularly, to replaceable filter cartridges used in household water filtration systems.
Many refrigerators are equipped with door-mounted drinking water and ice dispensers. Purified water is often supplied to such refrigerators via copper and plastic water supply lines from water filtration systems located under the kitchen sink. Some refrigerators, such as those sold under the GE® and HOTPOINT® brands, incorporate their own dedicated water filtration system of the type disclosed in U.S. Pat. No. 5,753,107 of Magnusson et al. Those dedicated filtration systems employ a removable filter cartridge which is typically replaced about every three months. The filter cartridge is located in the interior of the refrigerator and mates with a manifold using a bayonet locking scheme. The cartridge has a female end with a larger diameter, cylindrical recess and a concentric smaller diameter, cylindrical recess that depends from the larger diameter, cylindrical recess. The larger diameter, and smaller diameter, cylindrical cavities of the female end of the filter cartridge provide mating surfaces that mate with correspondingly sized male cylindrical bodies of the manifold, which are surrounded by O-rings to provide water-tight seals. Water passes through a spring biased inlet valve of the water filtration system into the cylindrical filter cartridge. The inlet valve cooperates with the filter cartridge to prevent forward flow of water until the filter cartridge is properly seated on the manifold via insertion and twisting. Water then passes from the inlet valve, downwardly to the bottom of the filter cartridge, and then upwardly through a core of the filter cartridge that contains various filtration media. Filtered water then exits the filter cartridge back into the manifold and passes through an outlet check valve that prevents back flow. The filtered water is then delivered to the ice maker and to the water dispenser.
These replacement filter cartridges do not have any O-rings located adjacent their mating surfaces and therefore to ensure against leaks the water filtration system is totally dependent on the integrity of the O-rings that surround the outside of the larger diameter and smaller diameter, male cylindrical bodies of the manifold to prevent water leakage. A slow leak in the water filtration system resulting from improper installation of the filer cartridge or failure of the O-rings that surround the male cylindrical bodies of the manifold may go unnoticed by the homeowner, leading to a larger diameter, amount of water leaking into the refrigerator and eventually onto the floor of the kitchen when finally discovered. Replacement filter cartridges for the aforementioned refrigerators may include an additional O-ring mounted in the bottom corner of the larger diameter, cylindrical recess of the filter cartridge in order to provide additional sealing capability.
A water filter cartridge is described in U.S. Pat. No. 8,216,463 that alters the water seal location between the manifold and the cartridge in the aforementioned water filtration systems and provides an indication of a leak immediately upon installation of the filter cartridge so that incorrect installation can be readily corrected and major water leakage avoided. That improved cartridge provides an open-sided, radial channel having a U-shaped cross section and that channel allows water leaking past the O-ring seals on the male projections to pass through the channel so that a user can look into the channel to check for water in order to see if a newly installed cartridge is leaking or to check for leaks thereafter. But the sealing ring is located at the bottom of a recess and requires that the U-shaped channel extend quite a distance along the length of the cartridge. The resulting disruption in the continuity of the cylindrical wall caused by the U-shaped channel weakens the wall. Additionally, the seal arrangement used in that patent is not compatible with more recent appliances which have manifolds that place protrusions such as radial ridges on a shoulder between the larger diameter and smaller diameter, male projections that extend from the manifold, so the radial ridges contact the O-ring seal used in that '463 patent and prevent a suitable water-tight seal from forming.
There is thus a need for a more convenient way to identify leaks in a wider variety of appliances, including appliances with protrusions on the end of the manifold members. There is also a need for a leak indicator that cooperates with the existing seals of the manifold. Also, because a channel with a U-shaped cross section weakens the annular wall bearing the mounting lugs, used to connect to the refrigerator manifold, there is a further need in some applications for a stronger connection while still allowing for leak checking.
Further, the U-shaped channel shown in U.S. Pat. No. 8,216,463 opens into an intervening chamber that surrounds the channel. Water leaking past the seal and into the U-shaped channel may fall into that chamber and be concealed from view if the amount of water is small. There is thus a need for an improved leak detection device that more readily shows a leaky seal resulting from an improper replacement of a water filter cartridge in a refrigerator or other appliance having replaceable water filters.